1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to managing security data, and more particularly, to securely managing security data between a host device and a secure multimedia card.
2. Description of the Related Art
Recently, digital rights management (DRM) has been actively researched and commercial services using DRM have already been implemented or will be implemented. DRM is a technical concept to protect digital content that can be illegally copied and distributed without permission.
Some efforts have been made to protect digital content. Generally, digital content protection has concentrated on preventing those without permission to access digital contents. Specifically, only those people who have paid fees are permitted to access the digital contents, and persons who have not paid the fees are denied access to the digital content. However, the digital contents can be readily copied, reused, processed and distributed to third parties due to the characteristics of the digital data. Accordingly, when a person who has paid the fees accesses the digital content and illegally copies or distributes it to a third party, the third party can use the digital content without paying the fees, which has produced a number of problems.
In order to solve these problems, in DRM, the digital content is encrypted and distributed, and a specified license called a rights object (RO) is needed to use the encrypted digital content.
FIG. 1 is a block diagram illustrating a structure of a host device and a secure multimedia card according to the related art.
As shown in FIG. 1, a host device 10 and a secure multimedia card 20 include connection portions between the host device 10 and the secure multimedia card 20 and enable communication by a physical contact or non-contact device. In a case of communication between peripheral devices, such as the host device 10 and the secure multimedia card 20, the host device 10 and the secure multimedia card 20 include interfaces 14 and 24 that become Universal Serial Bus (USB) ports or card readers, applications 13 and 23 serving as programs through which the host device 10 exchanges information with the secure multimedia card 20 and processes a communication protocol negotiation, file systems 12 and 22, each of which accesses a storage region of each device and manages the storage region such that a file or a directory can be read and written in the storage region, and storage regions 11 and 21, each of which is a physical region for storing data in each device and accesses the file system.
In this case, the host device 10 communicates with the secure multimedia card 20 to move security data, and transmits the security data to the secure multimedia card 20 or requests the secure multimedia card 20 to read the security data.
Further, the secure multimedia card 20 communicates with the host device 10 to move the security data, and receives or transmits the security data according to the request of the host device 10.
For reference, it is assumed that the security data used in exemplary embodiments of the present invention exists in types of files.
FIG. 2 is a flowchart illustrating a process of moving security data in a host device and a secure multimedia card according to the related art.
First, the host device 110 requests the secure multimedia card 20 to move (that is, read) the security data (S1). Then, the host device 10 reads the security data from the secure multimedia card 20 (S2), and stores the read security data in a storage space of the host device 10.
Then, the host device 10 transmits to the secure multimedia card 20, a signal informing that the security data is successfully stored (S3). Then, the secure multimedia card 20 deletes original security data (S4), and transmits to the host device 10, a signal informing that the movement of the security data is completed (S5).
As described above with reference to FIG. 2, in the DRM, when the security data is moved between two different devices, the security data should not exist in both of the two devices. In order to protect a right of a user, the security data should not get lost.
However, when connection between the host device 10 and the secure multimedia card 20 is separated while the host device 10 reads the security data in operation S2 of FIG. 2, the following problems may occur. That is, damaged security data is stored in the host device 10, and the secure multimedia card 20 removes the corresponding security data. As a result, the security data may not exist (that is, be lost) in both of the two devices.
Further, in the case where connection between the host device 10 and the secure multimedia card 20 is separated before the host device 10 completes movement of the corresponding security data and then informs the secure multimedia card 20 that movement of the corresponding security data is completed in operation S3 of FIG. 2, the secure multimedia card 20 does not know when the secure multimedia card 20 has removed a corresponding file. As a result, the same security data may exist (that is, be illegally copied) in both the host device 10 and the secure multimedia card 20.
Furthermore, when the two devices 10 and 20, of which the connection is not separated normally, are connected to each other again, it is not possible to confirm a current status of the corresponding security data, thereby not allowing an appropriate action to be taken in order to resolve the problems.